The Kimmeridge Clay is a

sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...

deposit of

fossiliferous A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved i ...

marine

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

which is of

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

to lowermost

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

age and occurs in southern and eastern England and in the

North Sea The North Sea lies between Great Britain, Denmark, Norway, Germany, the Netherlands, Belgium, and France. A sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Se ...

. This rock

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

is the major

source rock In petroleum geology, source rock is a sedimentary rock which has generated hydrocarbons or which has the potential to generate hydrocarbons. Source rocks are one of the necessary elements of a working petroleum system. They are organic-rich sedim ...

for

North Sea oil North Sea oil is a mixture of hydrocarbons, comprising liquid petroleum and natural gas, produced from petroleum reservoirs beneath the North Sea. In the petroleum industry, the term "North Sea" often includes areas such as the Norwegian ...

. The fossil fauna of the Kimmeridge Clay includes turtles,

crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term "crocodile" is sometimes used more loosely to include ...

sauropods Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...

plesiosaurs The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian st ...

pliosaurs Pliosauroidea is an extinct clade of plesiosaurs, known from the earliest Jurassic to early Late Cretaceous. They are best known for the subclade Thalassophonea, which contained crocodile-like short-necked forms with large heads and massive tooth ...

and

ichthyosaur Ichthyosauria is an order of large extinct marine reptiles sometimes referred to as "ichthyosaurs", although the term is also used for wider clades in which the order resides. Ichthyosaurians thrived during much of the Mesozoic era; based on fo ...

s, as well as a number of

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

species.

Description

Kimmeridge Clay is named after the village of

Kimmeridge Kimmeridge () is a small village and civil parish on the Isle of Purbeck, a peninsula on the English Channel coast in Dorset, England. It is situated about south of Wareham and west of Swanage. In 2013 the estimated population of the civil ...

on the

Dorset Dorset ( ; Archaism, archaically: Dorsetshire , ) is a Ceremonial counties of England, ceremonial county in South West England. It is bordered by Somerset to the north-west, Wiltshire to the north and the north-east, Hampshire to the east, t ...

coast of England, where it is well exposed and forms part of the

Jurassic Coast The Jurassic Coast, also known as the Dorset and East Devon Coast, is a World Heritage Site on the English Channel coast of southern England. It stretches from Exmouth in East Devon to Studland Bay in Dorset, a distance of about , and was ins ...

World Heritage Site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...

. Onshore, it is of Late Jurassic (

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 154.8 ±0.8 Ma and 149.2 ±0.7 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

) age and outcrops across England, in a band stretching from Dorset in the south-west, north-east to

North Yorkshire North Yorkshire is a Ceremonial counties of England, ceremonial county in Northern England.The Unitary authorities of England, unitary authority areas of City of York, York and North Yorkshire (district), North Yorkshire are in Yorkshire and t ...

. Offshore, it extends into the Lower Cretaceous (

Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 143.1 ±0.6 Ma and 137.05 ± 0.2 (million years ago) ...

Stage) and it is found throughout the Southern, Central and Northern North Sea. The foundations of the

Humber Bridge The Humber Bridge is a single-span road suspension bridge near Kingston upon Hull, East Riding of Yorkshire, England. When it opened to traffic on 24 June 1981, it was the longest of its type in the world; the Akashi Kaikyō Bridge surpassed ...

on the southern (Barton) side of the bridge are on Kimmeridge Clay beneath superficial deposits, under the

Humber The Humber is a large tidal estuary on the east coast of Northern England. It is formed at Trent Falls, Faxfleet, by the confluence of the tidal rivers River Ouse, Yorkshire, Ouse and River Trent, Trent. From there to the North Sea, it forms ...

estuary.

Economic importance

Kimmeridge Clay is of great economic importance, being the major

for oil fields in the North Sea hydrocarbon province. It has distinctive physical properties and log responses.

Vertebrate fauna

Fauna uncovered from the Kimmeridge Clay include:Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 545–549. .

Ray-finned fish

Lobe-finned fish

Cartilaginous fish

Turtles

Archosaurs

Thalattosuchians

Ornithischians

Indeterminate ankylosaur osteoderms have been found in Wiltshire, England. Indeterminate stegosaurid remains have been found in Dorset and Wiltshire, England.

Saurischians

Indeterminate ornithomimmid remains have been found in Dorset, England. An undescribed theropod genus was found in Dorset.

Pterosaurs

Plesiosaurs

Ichthyosaurs

Invertebrates

The invertebrate fauna of the Kimmeridge Clay includes:http://www.fullbooks.com/The-Student-s-Elements-of-Geology7.html The Student's Elements of Geology by Sir Charles Lyell Part 7 out of 14 accessed 13 February 2009. *

Mollusca Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

: **'' Cardium striatulum'' ** '' Ostrea deltoidea'' ** ''Gryphaea'' (''Exogyra'') ''virgula'' ** '' Trigonellites'' ** '' Belemnotheutis'' **'' Etchesia'' *

Arthropoda Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an exoskeleton with a cuticle made of chitin, often mineralised with calcium carbonate, a body with differentiated ( metameric) segments, and paired jointed appendages. ...

: **'' Phlyctosoma sp.'' ** ''

Eryma ''Eryma'' is a genus of fossil lobster-like crustaceans, containing 44 species. The oldest known species was discovered in non-marine deposits from the late Triassic Chinle Formation located in the Petrified Forest National Park, Arizona. Two oth ...

sp.'' ** '' Magila latimana'' ** ''

Mecochirus ''Mecochirus'' is an extinct genus of lobster-like decapod crustaceans, containing 17 species. The Maxberg Specimen of ''Archaeopteryx ''Archaeopteryx'' (; ), sometimes referred to by its German name, "" ( ''Primeval Bird'') is a genus ...

sp.'' ** '' Archaeolepas redtenbacheri''

References

Bibliography

* Galton, P.M. 1999. Cranial anatomy of the hypsilophodontid dinosaur Bugenasaura infernalis (Ornithischia: Ornithopoda) from the Upper Cretaceous of North America. Revue Pale´obiologie, 18, 517–534.